Stabilizing system for a knee brace

ABSTRACT

A knee brace for assisting the extension or flexing of a limb comprises substantially rigid upper and lower frames connected by a hinge, the upper frame being secured to the leg by an upper strap. A stabilizing strap for fixing the lower frame to the user&#39;s leg comprises an inelastic band, cord or other flexible securing member for circumscribing the user&#39;s leg having a fastening element for fixing the securing member in a set position. The securing member is affixed to the arms of the lower frame, slidably extending through at least one strap support provided by at least one of the arms of the lower frame. When the brace is in position on a user&#39;s leg the stabilizing strap is able to move through at least one strap support in a generally horizontal direction while supporting the lower frame in the vertical direction.

FIELD OF THE INVENTION

This invention relates to braces, and in particular a knee brace forsupporting and/or assisting the extension of a user's leg.

BACKGROUND OF THE INVENTION

As is well known, a brace can perform a purely prophylactic function, orprovide an assistive force that helps the user to extend their limb, orboth. Knee braces in particular can provide physical protection againstinjury, and may for example be used by athletes involved in high-risksports where there is a relatively high susceptibility to sustaining aknee injury.

Many individuals suffer from knee problems, often due to a prior kneeinjury. Some such problems can significantly affect mobility and/or theability to support the injured person. While corrective measures such asexercise and physiotherapy, or in more serious cases surgery, can assistin correcting or partially alleviating some knee problems, there remainsa need in many cases for knee support and extension augmentation.

Particularly where there has been ligament damage, for example a tear orstrain in the anterior cruciate ligament (ACL), medial collateralligament (MCL) or lateral collateral ligament (LCL), a knee brace can beused to both provide support and enhance extension strength, and thusreduce the load on the injured knee. Conventional knee braces thatprovide active assistance to knee extension are designed to yield whenthe knee is flexed, loading a torsion spring or compression spring inthe process. The spring is loaded when the user bends their leg, andwhen extending their leg the spring unloads applying a force thataugments the extension action. This also helps to support the user andprevent collapse if the injured knee buckles.

A substantial force is required to significantly enhance knee extensionand resist buckling of the knee. An example of a knee brace capable ofproviding the required force is described and illustrated in U.S. patentapplication Ser. No. 14/526,826 filed Oct. 29, 2014 entitled BRACE ANDTENSION SPRINGS FOR A BRACE, which is incorporated herein by referenceand referenced by way of non-limiting example only. This brace designprovides effective enhancement of the knee extension action in caseswhere strength enhancement is needed and resistance to buckling of theknee.

However, the forces imparted by the springs in the aforesaid bracecreate problems with maintaining the correct position of the brace inuse. The brace has substantially rigid upper and lower frames whicharticulate about a joint, typically a polycentric hinge. The upper andlower frames are in turn secured to the leg above and below the knee,respectively, often by straps secured around the leg. Since the anklecannot be used to support the brace because this would inhibit use ofthe foot, in a conventional knee brace the strap securing the lowerframe to the user's leg is typically secured above the calf (since belowthe calf the leg tapers in a downward direction). However, because ofthe large forces involved, even where a strap is secured above the calfover repeated cycles the brace will tend to migrate down the user's leg.This problem is exacerbated by the fact that the cross-sectional shapeof the leg changes slightly as the leg moves

It would accordingly be advantageous to provide a stabilizing system fora brace that stabilizes the brace in a set position over repeatedextension cycles.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate one or more embodiments of the invention byway of example only,

FIG. 1 is a rear elevation of a lower frame of a brace embodying astabilizing system according to the invention utilizing an inelasticband.

FIG. 2 is a side elevation of the lower frame shown in FIG. 1.

FIG. 3 is a front perspective view of the lower frame shown in FIG. 1.

FIG. 4 is a front elevation of the lower frame shown in FIG. 1.

FIG. 5 is a rear elevation of a lower frame of a brace stabilizingsystem according to the invention utilizing an inelastic cord.

FIG. 6 is a side elevation of the lower frame shown in FIG. 5.

FIG. 7 is a front perspective view of the lower frame shown in FIG. 5.

FIG. 8 is a front elevation of the lower frame shown in FIG. 5.

FIG. 9 is a side elevation of a brace according to the invention mountedto a user's leg.

FIG. 10 is a front elevation of the brace of FIG. 9.

FIG. 11 is a rear elevation of the lower frame of a brace employing afurther embodiment of a stabilizing system according to the invention.

FIG. 12 is a front elevation of the lower frame shown in FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described in the context of a knee brace forhumans. However, it will be appreciated that the principles of theinvention can be applied to braces for other human body appendages andto braces for animals including (without limitation) horses, dogs andcats.

The invention thus provides a knee brace for assisting the extension orflexing of a limb, comprising substantially rigid upper and lower framesconnected by a hinge, the upper frame comprising hinge arms each havingone end connected to the hinge and an opposite end connected to theother hinge arm by an upper leg bearing member for bearing against auser's leg above the knee, the lower frame comprising hinge arms eachhaving one end connected to the hinge and an opposite end connected tothe other hinge arm by a lower leg bearing member for bearing against auser's leg below the knee, at least one upper securing member for fixingthe upper frame to the user's leg, and a stabilizing strap for fixingthe lower frame to the user's leg, comprising an inelastic element forcircumscribing the user's leg having a fixing element for securing theband in a set position, the band slidably extending through at least onestrap support provided by at least one of the arms of the lower frameand being affixed to the other of the arms of the lower frame, such thatwhen the brace is in position the stabilizing strap is able to movethrough the at least one strap support in a generally horizontaldirection while supporting the lower frame in the vertical direction.

The invention further provides, for a knee brace for assisting theextension or flexing of a limb, the knee brace comprising substantiallyrigid upper and lower frames connected by a hinge, the upper framecomprising hinge arms each having one end connected to the hinge and anopposite end connected to the other hinge arm by an upper leg bearingmember for bearing against a user's leg above the knee, the lower framecomprising hinge arms each having one end connected to the hinge and anopposite end connected to the other hinge arm by a lower leg bearingmember for bearing against a user's leg below the knee, and at least oneupper securing member for fixing the upper frame to the user's leg, astabilizing system comprising: a stabilizing strap for fixing the lowerframe to the user's leg, comprising an inelastic element forcircumscribing the user's leg having a fixing element for securing theband in a set position, the band slidably extending through at least onestrap support provided by at least one of the arms of the lower frameand being affixed to the other of the arms of the lower frame, such thatwhen the brace is in position the stabilizing strap is able to movethrough the at least one strap support in a generally horizontaldirection while supporting the lower frame in the vertical direction.

In the illustrated example of a brace 10 according to the invention, alower frame 14 is pivotally connected to an upper frame 12 as hinge 16,so that the upper and lower frames 12, 14 can pivot relative to eachother. As shown in FIGS. 9 and 10, when the knee brace is in positionthe pivots 16, 17 are respectively disposed on either side of the legalong the axis of rotation of the knee 6, and the frames 12, 14 thusfreely pivot relative to one another as the knee 6 flexes and extends.In other embodiments the frames 12, 14 may be geared to each other, orotherwise coupled by a linkage such that they rotate in synchronization.

The knee brace 10 illustrated applies a force to assist the user inextending the knee 6 when the knee 6 has been flexed. This restoringforce is supplied by a loading system 18, which can be any suitableloading system including (without limitation) the tension springsdescribed and illustrated in U.S. patent application Ser. No.14/526,826, which is incorporated herein by reference.

According to the invention, a securing system for a brace 10 comprises asingle stabilizing strap 20 affixed to the lower frame 14 of the brace10 in the manner hereinafter described, which circumscribes the entirecircumference of the lower leg at a position between the bottom of theknee 6 and top of the calf muscle. When adjusted the stabilizing strap20 uniformly tightens around the leg, providing a secure fit.

In the embodiment illustrated the knee brace comprises a substantiallyrigid upper frame 12 and a substantially rigid lower frame 14 connectedby opposed hinges 16. The frame portions 12, 14 may be formed frommetal, plastic, fiberglass or any other relatively rigid material whichis preferably lightweight, durable and capable of withstanding theelements (for wearing in inclement weather).

The upper frame 12 comprises hinge arms 12 a, 12 b each having one endconnected to the hinge 16 and an opposite end connected to the otherhinge arm by an upper leg bearing member 12 c for bearing against auser's leg above the knee 6. The lower frame 14 similarly compriseshinge arms 14 a, 14 b each having one end connected to the hinge 16 andan opposite end connected to the other lower frame hinge arm by a lowerleg bearing member 14 c for bearing against a user's leg below the knee.

The upper frame 12 is fixed to the user's leg by an upper securingmember, as shown an upper strap 19, located so as to bear against theleg above the knee 6. The upper strap 19 serves to hold the leg bearingmember 12 c securely against the user's quadriceps, so that when the legis bent the brace 10 bends along with the leg at hinges 16.

The lower frame 14 is fixed to the user's leg by a stabilizing strapcomprising a flexible, substantially non-stretchable securing member. Inthe embodiment illustrated in FIGS. 1 to 4 the securing member comprisesan inelastic tensioning band 22, for example made from nylon or anothersubstantially non-stretchable material, for circumscribing the user'sleg. The band 22 comprises a releasable fixing element 24 for securingthe band 22 in a desired position at a selected tension, in theembodiment illustrated a hook-and-loop fastener such as Velcro(Trademark). Other fasteners capable of retaining the band 22 in with aset circumference, including without limitation hook-and-eye fasteners,grapple grommets, toggle levers and lacing, may also be used. Forconvenience and ease of use, fasteners that are easy to fasten and donot change the selected circumference of the band 22 when fastened arepreferred.

The band 22 is affixed to the arms 14 a, 14 b of the lower frame 14. Theband 22 slidably extends through at least one arm 14 a, 14 b, forexample through one or more strap supports 40 projecting from, affixedto or otherwise provided by at least one arm 14 a, 14 b.

In the embodiments shown in FIGS. 1 to 4 the strap supports comprise atleast one strap retaining member 40, such as a steel ring or bight thattraps the strap 22 in horizontally slidable relation, affixed to theinterior surface of each arm 14 a, 14 b at any desired position alongthe arms 14 a, 14 b. Thus, when the brace 10 is in position on theuser's leg the stabilizing strap 20 is movable through the strapsupports 40 in a generally horizontal direction but not in a verticaldirection, to thereby support the lower frame in the vertical directionwhile ‘floating’ in the horizontal direction. The strap supports 40 maybe formed from any suitable material and affixed to or integrated intothe lower frame 14 in any suitable fashion. For example, the strapsupports 40 may be fixed to a plastic or rubberized backer that is inturn fixed to the lower frame 14 with a single point of contact (forexample riveted).

In the embodiment shown in FIGS. 11 and 12 at least one strap retainingmember 40 such as a steel ring or bight is affixed to the interiorsurface of one arm, 14 a in the embodiment shown, at the desiredposition; and the strap 22 is fixed to the other arm, 14 b in theembodiment shown, in both horizontally and vertically fixed relation,for example by a bolt, rivet or any other suitable fastener 41 affixingthe strap 22 directly to the arm 14 b. Alternatively, the fastener mayinclude a quick-connect coupler such as a luggage strap connector 43 asshown, one end of which is fixed to the arm 14 b (also by a bolt, rivetor any other suitable fastener), for ease of attaching the brace 10 tothe user's leg. Thus, when the brace 10 is in position on the user's legthe stabilizing strap 20 is movable through the strap support 40 on onearm (e.g. 14 a) in a generally horizontal direction but not in avertical direction, to thereby support the lower frame in the verticaldirection while ‘floating’ in the horizontal direction, while thestabilizing strap 20 is fixed by fastener to the other arm (e.g. 14 b)to prevent the strap 22 from moving in any direction relative to the arm14 b. This provides essentially the same ability, overall, for the strap22 to ‘float’ in the horizontal direction. The stabilizing strap 20comprises a rear shell 26 which partially or fully overlies the calfmuscle, for load bearing purposes. The band 22 is fixed to (or around)the exterior surface of the shell 26, which may be formed fromcarbon-fibre so as to be durable and semi-rigid, but is preferablyformed thin enough to be flexible so as to largely yield to the shape ofthe calf for stability and comfort. If the band 22 is not sufficientlycomfortable by itself, the stabilizing strap 20 may optionally furthercomprise a front pad 28 for comfort, which can also be formed fromcarbon-fibre or may comprise a flexible cushioning pad that spreads theload of the tightened band 22 over a larger portion of the user's shin.

In a conventional brace the securing strap is tightened against thebrace frame, rather than solely against the leg. This can leads to thestrap being over-tight on one of the front or back of the frame and tooloose on the other, which in turn can lead to brace migration anddiscomfort. Even when a strap is properly tensioned against the braceframe in a static position, as the leg changes shape and position duringmotion the strap can migrate into a different position. When astabilizing strap 20 according to the invention is mounted to the lowerframe 14, tensioning the stabilizing strap 20 loads the front and backof the band 22 against each other, this constricting the strap 22 onlyagainst the user's leg, rather than loading the strap 22 against thelower frame 14. The resulting freedom of motion in a horizontal planeallows for more precise tightening of the stabilizing strap 20 for botheffectiveness and comfort, and allows the stabilizing strap 20 to followleg's motion and changes in shape as it is bent without shifting theposition of the brace 10.

A brace 10 according to the invention is thus designed to securely graspa users' lower leg and restrict vertical brace migration. Allowing thestabilizing strap 20 to move through supports 40 on (or integrated into)the lower frame 14 in a horizontal plane facilitates a uniform pressureof the stabilizing strap 20 around the leg for a secure fit, securelyclinching the leg and restricting the motion of the strap in a verticaldirection to eliminate vertical brace migration.

In use, the brace 10 is placed over the user's leg at the correctposition with the hinge 16 in alignment with the knee 6, and the upperframe 12 is secured above the knee. The rear shell 26 is positioned overthe rear of the leg, overlapping the calf muscle partially or fully, andthe front pad 28 is centred over the user's shin. The tensioning band 22is tightened to the desired loading and the fastener 38 is engaged tofix the stabilizing strap 20 in position. The stabilizing strap 20 thensupports the brace 10 vertically, to maintain the desired verticalpositioning, but is able to move in a horizontal plane and thusaccommodate the changing shape and exterior profile of the leg when theuser is in motion.

A further embodiment of the invention is illustrated in FIGS. 5 to 10.In this embodiment the stabilizing strap 30 comprises a rear shell 36which partially or fully overlies the calf muscle for load bearingpurposes, and may further comprise a front pad 38 for comfort, asdescribed above in relation to the previous embodiment. The flexibletensioning member in this embodiment comprises at least one inelastictensioning cord 32, for example made from nylon lacing or anothersubstantially non-stretchable material, for circumscribing the user'sleg.

In this embodiment the strap supports through which the cord 32 slidablyextends comprise holes 33 disposed transversely through the lower frame14 so that, as in the previous embodiment, the tensioning member 32‘floats’ in a horizontal plane and can thus move independently of thelower frame 14 in a horizontal plane while supporting the lower frame 14vertically.

The cord 32 is affixed to, around or through the front pad 38,preferably in slidable relation so that the front pad 38 is able to moverelative to the cord 32 and can thus always be positioned over the shincentrally between the arms 14 a, 14 b, regardless of the size of theuser's leg or the amount of tension applied to the cord 32.

The cord 32 is also affixed to, around or through the rear shell 36. Inthe embodiment illustrated a single piece of lace or other material isused for the tensioning cord 32, doubled so as to circumscribe theuser's leg twice when in use. As best seen in FIG. 7 the cord 32 isdisposed through the front pad 38, extending through holes in a rigid orsemi-rigid backing layer 38 b and thus slidably received between aninner cushioning layer 38 a and the backing layer 38 b. Since a singlecord 32 is used in this embodiment, the cord 32 crosses over itselfwithin the front pad 38 so that the two circumscribing portions of thecord 32 can be spaced apart, preferably disposed near top and bottomedges of the front pad 38 and rear shell 36 to distribute the loadingforce.

In this embodiment the rear shell 36 comprises a tightening knob 34, forexample affixed to the rear shell 36 around which the cord 32 is woundsuch that rotating the knob 34 tightens or loosens the tension on thecord 32, allowing for a proper fit regardless where the lower frame 14sits on the leg and to accommodate legs of different sizes. Thetightening knob 34 actuates a reel (not shown) embedded in the rearshell 36, that the cord 32 winds onto or pays off from, which tightensthe upper circumscribing portion of the cord 32 as the user bends theirleg. The cord 32 naturally slides through the lower frame 14 and frontpad 38 to equalize the tension. The knob may be affixed to the reel by areleasable ratchet or other mechanism which maintains tension on thecord 32 until released by the user. Thus, when the knob 34 is rotated totighten the cord 32 the shell 36 and front pad 38 securely clinch thelower leg.

The embodiment in which the securing member is horizontally slidablerelative to one of the lower arms 14 a, 14 b and horizontally fixedrelative to the other of the lower arms 14 a, 14 b also applies toembodiments utilizing an inelastic cord 32 or other securing member. Inthe case of a cord 32, the cord 32 can be horizontally fixed to theother of the arms 14 a, 14 b in any suitable fashion, including forexample by forming a male or female coupler component in the arm itself;by filling the hole 33 with epoxy or another curable compound oradhesive; by fitting a plug or screw into the hole 33; by knotting thecord on either side of the arm; or in any other suitable fashion.

Various embodiments of the present invention having been thus describedin detail by way of example, it will be apparent to those skilled in theart that variations and modifications may be made without departing fromthe invention. The invention includes all such variations andmodifications as fall within the scope of the appended claims.

1. A knee brace for assisting the extension or flexing of a limb,comprising substantially rigid upper and lower frames connected by ahinge, the upper frame comprising hinge arms each having one endconnected to the hinge and an opposite end connected to the other hingearm by an upper leg bearing member for bearing against a user's legabove the knee, the lower frame comprising hinge arms each having oneend connected to the hinge and an opposite end connected to the otherhinge arm by a lower leg bearing member for bearing against a user's legbelow the knee, at least one upper securing member for fixing the upperframe to the user's leg, and a stabilizing strap for fixing the lowerframe to the user's leg, comprising an inelastic element forcircumscribing the user's leg having a fixing element for securing theband in a set position, the band slidably extending through at least onestrap support provided by at least one of the arms of the lower frameand being affixed to the other of the arms of the lower frame, such thatwhen the brace is in position the stabilizing strap is able to movethrough the at least one strap support in a generally horizontaldirection while supporting the lower frame in the vertical direction. 2.The knee brace of claim 1 wherein the inelastic element comprises aband.
 3. The knee brace of claim 2 wherein the at least one strapsupport comprises a ring or bight through which the band is slidablyreceived.
 4. The knee brace of claim 3 wherein the strap support affixedto the other of the arms of the lower frame is affixed in horizontallyslidable relation.
 5. The knee brace of claim 3 wherein the strapsupport affixed to the other of the arms of the lower frame is affixedin fixed relation.
 6. The knee brace of claim 5 wherein the strapsupport comprises a quick-connect coupler.
 7. The knee brace of claim 1wherein the inelastic element comprises a cord.
 8. The knee brace ofclaim 7 wherein the at least one strap support comprises an openingthrough one of the arms through which the band slidably extends.
 9. Theknee brace of claim 8 wherein the strap support affixed to the other ofthe arms of the lower frame is affixed in horizontally slidablerelation.
 10. The knee brace of claim 8 wherein the strap supportaffixed to the other of the arms of the lower frame is affixed in fixedrelation.
 11. For a knee brace for assisting the extension or flexing ofa limb, the knee brace comprising substantially rigid upper and lowerframes connected by a hinge, the upper frame comprising hinge arms eachhaving one end connected to the hinge and an opposite end connected tothe other hinge arm by an upper leg bearing member for bearing against auser's leg above the knee, the lower frame comprising hinge arms eachhaving one end connected to the hinge and an opposite end connected tothe other hinge arm by a lower leg bearing member for bearing against auser's leg below the knee, and at least one upper securing member forfixing the upper frame to the user's leg, a stabilizing systemcomprising: a stabilizing strap for fixing the lower frame to the user'sleg, comprising an inelastic element for circumscribing the user's leghaving a fixing element for securing the band in a set position, theband slidably extending through at least one strap support provided byat least one of the arms of the lower frame and being affixed to theother of the arms of the lower frame, such that when the brace is inposition the stabilizing strap is able to move through the at least onestrap support in a generally horizontal direction while supporting thelower frame in the vertical direction.
 12. The stabilizing system ofclaim 11 wherein the inelastic element comprises a band.
 13. Thestabilizing system of claim 12 wherein the at least one strap supportcomprises a ring or bight through which the band is slidably received.14. The stabilizing system of claim 13 wherein the strap support affixedto the other of the arms of the lower frame is affixed in horizontallyslidable relation.
 15. The stabilizing system of claim 13 wherein thestrap support affixed to the other of the arms of the lower frame isaffixed in fixed relation.
 16. The stabilizing system of claim 15wherein the strap support comprises a quick-connect coupler.
 17. Thestabilizing system of claim 11 wherein the inelastic element comprises acord.
 18. The stabilizing system of claim 17 wherein the at least onestrap support comprises an opening through one of the arms through whichthe band slidably extends.
 19. The stabilizing system of claim 18wherein the strap support affixed to the other of the arms of the lowerframe is affixed in horizontally slidable relation.
 20. The stabilizingsystem of claim 18 wherein the strap support affixed to the other of thearms of the lower frame is affixed in fixed relation.